The OFDMA system is a system that divides a frequency domain into sub-channels and a time domain into symbols in frequency—time domains of OFDMA frames and allocates bandwidths as slots that represent the divided domains to users. The OFDMA system has been used for example in WiMAX (Worldwide Interoperability for Microwave Access).
OFDMA-based radio communication apparatuss have been focused on low cost and power saving of a transmission amplifier that amplifies transmission signals. However, the transmission amplifier has a problem in which non-linear distortion occurs.
Thus, the OFDMA-based radio communication apparatuss commonly use a distortion compensation unit so as to reduce the influence of non-linear distortion involved in the transmission amplifier.
The distortion compensation unit ordinarily generates distortion compensation coefficient data that serve to compensate for non-linear distortion involved in the transmission amplifier. However, in order to obtain the distortion compensation coefficient data, it is necessary to generate a learning signal.
A technique that generates such a learning signal is presented, for example, in Patent Literature 1. According to the technique presented in Patent Literature 1, a distortion compensation unit uses a learning signal generator and a frame generator so as to generate the learning signal.